Propeller blade



June 10, 1947. L. A. HEINTZELMAN 2,422,098

PROPELLER BLADE Filed Jan. 26, 1944 3 Sheets-Sheet 1 Zea /7. {151/2 72 61/7700 Lo By Q 6 I nFune 10, 1947.

I. A. HEINTZELMAN PROPELLER BLADE Filed Jan. 26 1944 5 Sheets-Sheet 2 June 10, 1947. I L. A. HEENTZELMAN 2,422,098

PROPELLER BLADE Filed Jan. 26 1944 5 Sheets-Sheet 3 Patented June 10, 1947 UNITED stares Parana creme PROBELLER BIJA'DE L-eoA. Heintzelman, Grand-Rapids, Mich.

Application January 26, 1344;- Serial "No. 519,803

' 1 Claim.

Thepresent invention relates tonew and usefulrimprovements in blades, particularly for airplane propellers, although ittwill-be understood, of? coursaathat the. blade may.- be used for. any other purpose for which it may be found adapted and desirable, such as for boat propellers, fans, et cetera.

Th primary object of the invention is to provide, in a manner as hereinafter set forth, a propeller or fan blade of the character described comprising a novel shape or construction whereby noise will be materially reduced or substantially eliminated.

Other objects of the invention are to provide a propeller or fan blade of the aforementioned character which will be comparatively simple in construction, strong, durable, highly eflicient in use and which may be manufactured at low cost.

All of the foregoing and still further objects and advantages of the invention will become apparent from a study of the following specification, taken in connection with the accompanying drawing wherein like characters of reference designat corresponding parts throughout the several views, and wherein:

Figure 1 is a view in front elevation of a blade constructed in accordance with the present invention.

Figure 2 is a plan view thereof.

Figures 3 to 11, inclusive, are cross-sectional views, taken substantially on the correspondingly numbered section lines of Figure 1.

Figure 12 is a view in front elevation of another form of the invention.

Figure 13 is a plan view of the modification.

Figures 14 to 22, inclusive, are cross-sectional views, taken substantially on the correspondingly numbered section lines of Figure 12.

In the embodiments which have been illustrated, the invention is incorporated in an airplane propeller comprising a hub l. The blade, which is designated generally by reference numeral 2, is of suitable wood and projects from the hub I.

Th blade 2 is in the form of an obtuse-angled triangle in cross-section substantially throughout its length, said blade including a substantially V-shaped rib 3 which extends from a point adjacent the hub I to a point adjacent the free end portion of said blade. The apex of the rib 3 is closer to the leading edge 4 of the blade 2 than to the trailing edge 5 thereof. Thus, a comparatively narrow flat surfac 6 is formed on the forward portion of the front of the blade 2, which construction also provides f a -relatively"wide; flat" surface 1 whichextends from theapexnfthe rib- 3 to the trailing" edge 5' of the blade The back of the blade 2 includes a single, flat surface 8 extending between the leading and trailing edges l and 5.

The rib 3 terminates in a reversely curved outer end portion 9 (see Fig. 1) which merges into the trailing edge 5 of the blade 2. Also, the leading and trailing edges of the blade are similarly outwardly bowed so that said blade symmetrically decreases in width from a, point near but inwardly of the transverse center of the blade to the hub and the tip of the blade.

In use, the propeller turns in a clockwise direction as viewed in Figure 1 of the drawing. The leading edge 4 of the blade 2 cuts through the air which travels over the surface 6 past the apex of the rib 3, said air leaving said blade in substantially the plane of said surface 6 thus avoiding the surface I. In this manner the air is prevented from flowing around the trailing edge 5 of the blade and noise from this source is eliminated or prevented. Reversely curved outer end portion 9 of the rib 3 permits the air current to slip off both to the rear and to thc side of the blade with a minimum of noise. This construction also reduces vibration by tending to relieve pressure at the tip of the blade. The construction is also such as to materially strengthen the blade.

In Figures 12 to 22, inclusive, of the drawing, a hollow blade of suitable metal is designated generally by reference numeral Ill, said blade projecting from a hub II.

The metallic blade ID is also substantially triangular in cross-section and includes a flat back :2 having mounted thereon and rigidly secured in any suitable manner a substantially V-shaped front !3 of comparatively light or thin stock. Projecting from the back l2 of the hollow metallic blade H! is an integral brace l4 for the front 13.

The blade It] functions in a manner substantially similar to the wood blade 2. However, the metallic blade Ill is thin as compared with the wood blade 2 and the forward surface l5 of the front l8 is comparatively wide with the rear surface It proportionately narrower. The leading and trailing edges of the blade H) are indicated, respectively, at I! and Hi.

It is believed that the many advantages of a propeller or fan blade constructed in accordance with the present invention will be readily under- 3 stood, and although preferred embodiments of the device are as illustrated and described, it is to be understood that further modifications and changes in the details of construction may be resorted to which will fall within the scope of the invention as claimed.

What is claimed:

A propeller including a hub, and a blade projecting from the hub and disposed at an angle to the axis of the propeller, said blade having leading and trailing edges similarly slightly bowed outwardly so that the blade symmetrically decreases in width from a point near but inwardly of the transverse center of the blade to the hub and the tip of the blade, said blade further being in the form of an obtuse-angled triangle in each cross section substantially throughout its length so as to provide a flat rear surface extending between the leading and trailing edges and a'V-shaped front surface whoseapex is nearly straight and located nearer to the leading edge of the blade than to the trailing edge thereof, said apex terminating at its outer end adjacent but inwardly of the tip edge of the blade and having its outer end curved toward and merging with the trailing edge. V

LEO A. HEINTZELMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany Sept. 28, 1920 

